Characterizing the Deep Terrestrial Subsurface Microbiome

A large portion of the earth's biomass resides in the subsurface and recent studies have expanded our knowledge of indigenous microbial life. Advances in the field of metagenomics now allow analysis of microbial communities from low-biomass samples such as deep (>2.5 km) shale core samples. Here we present protocols for the best practices in contamination control, handling core material, extraction of nucleic acids, and low-input library preparation for subsequent metagenomic sequencing.